In mobile and wireless communication technology, multiple carrier frequency communication schemes gain more and more interest for their ability to cope with intersymbol interference (ISI). In such a system, the bits (or symbols) of a serial data stream are distributed onto a plurality of subchannels associated with different carrier frequencies, thereby reducing the bit rate in each of the subchannels. Due to the reduced bit rate in each subchannel, this communication scheme is less susceptible against intersymbol interference compared to a single carrier communication scheme operating under same or similar delay time constraints.
There are a plurality of publications dealing with multi carrier communication schemes in general, and with OFDM schemes in particular. A general overview of multi carrier systems can be found, for instance, in “A Time Domain View to Multi-Carrier Spread Spectrum” by Fettweis, Nahler, and Kühne, IEEE 6th International Symposium on Spread-Spectrum Technology and Applications, New Jersey, USA, September 2000.
Furthermore, it is known to exploit so-called pilot symbol assisted channel estimation techniques to track channel variations in the communication process. In this connection, so-called pilot symbol assisted modulation (PSAM) might be used for transmitting and receiving a data stream. Pilot symbols are known “training symbols” that are multiplexed into the data stream at certain sub-channels (carrier frequencies) in order to derive the varying channel characteristics from the known characteristics of the training symbols. There are a plurality of publications directed to channel estimation using pilot symbols and, vice versa directed to designing appropriate pilot symbol patterns. Reference is made, for instance, to “Pilot Assisted Channel Estimation for OFDM in Mobile Cellular Systems” by Tufvesson and Masing, Proceedings of IEEE Vehicular Technology Conference, Phoenix, USA, pp. 1639-1643, 1997 and “Pilot-Assisted Channel Estimation in MC-CDMA for Future Mobile Cellular Systems” by McKeown et al., Proceedings of the London Communications Symposium 2002.
So far, however, there has not been made deeper consideration on how to allocate a specific communication signal to selected ones of the multiple carrier frequencies in a multi carrier spread spectrum scenario. It is therefore an object of the present invention to provide a method and a corresponding device for allocating a communication signal to multiple carrier frequencies (sub-channels) in such a communication environment.